Temperature-controlled timer



May 15, 1962 H. N. DURHAM 3,034,283

TEMPERATURE-CONTROLLED TIMER Filed Aug. 18, 1958 /4 3h /8 INVENTOR.

flaamr M DURHAM A TTORNEKS.

United States The present invention relates to a novel and improved temperature controlled timer which is adapted to register the total of the periods of time it is subjected to a temperature in excess of a predetermined temperature.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention.

of the drawings: 7

FIGURE 1 is a top plan view of the preferred and illustrative embodiment of the present invention, with the cover of the case removed;

FIGURE 2 is a top plan view of the timer in its casmg;

FIGURE 3 is a fragmentary detailed top plan view, with certain parts in section and others broken away of the mechanism shown in FIGURES 1 and 2;

FIGURE 4 is a developed vertical sectional view through the mechanism of FIGURES 1 to 3, and showing the gears as though their axes were in a single plane; and

FIGURE 5 is a fragmentary vertical section view of a modification of the present invention.

The present invention has for an object the provision of a novel and improved temperature controlled timing mechanism which is simple, economically manufactured and is sharply responsive to a given temperature. A further object is the provision of a temperature controlled timing mechanism which can be manufactured and will be accurately controlled as to its periods of running without the necessity of individually adjusting each timer. Still another object of the invention is the provision of a timer which is temperature controlled in its running and which will retain the accuracy of its control over a long period of time and without mechanical adjustment.

In accordance with the present invention there is provided a timing mechanism having a powered gear train which is adapted to run at a substantially constant rate, when it runs, and is provided with means for indicating the time of running of the train and which is provided with a normally solid element engaging a portion of the gear train to prevent running of the gear train, which element becomes fluid when heated in excess of a predetermined temperature and thereby permits the gear train to run and the indicator to progress to totalize the periods of time that said element (and the timer) has been heated to a temperature in excess of said predetermined temperature. Preferably the timing apparatus (except for a springwinding knob which often serves also as the total indicator), is enclosed within a substantially waterproof and air-tight casing. The normally solid element may be a mass of a substance which melts at the desired temperature. For this purpose, it may be a metal alloy, such as a low melting alloy, similar to Woods metal, although it is usually preferable to avoid a substance having a melting range and to use a relatively pure chemical compound or substance which has a sharp melting point which is substantially the same as its freezing point. It is also preferable, for extended service, that the melting substance should be substantially non-volatile at its service temperature, although for certain applications, it may be more economical to provide for periodic replacement of the melting substance than to use a non-volatile substance which melts at substantially the same temperature. To reduce volatilization of the melting substance it may be enclosed within a closed cap fast to a frame plate and holding the melting substance in contact with the end of a gearing shaft, which may be non-circular in shape to provide a more positive grip on the shaft end.

The temperature controlled timing mechanisms of the present invention have a wide range of usefulness in determining the total period of time that the timer, and adjacent objects have been subjected to temperatures in excess of a given value. Thus, using a substance melting at about 120 C. they may be used to indicate the total period of time that the timer and its surrounding objects have been subjected to a temperature in excess of 120 C., thereby indicating that the adjacent objects have been adequately sterilized in an atmosphere of steam.

In another exemplary application, the timers may be used to indicate whether or not a shipment of bottles of whole blood have been subjected to a temperature in excess of 50 F. for more than a given total time, e.g. 12 hours. Or, in the shipment of frozen foods, the timing mechanisms may be used to indicate whether the packaged foods have been subjected to external temperatures in excess of a given value for a total of a given number of hours, to indicate whether or not the packages may have thawed or not, thereby indicating the possibility that the packaged food may be subject to spoilage and cannot be stored and sold as properly shipped and stored frozen food.

The apparatus of the present invention is not infallibly self-restarting whenever its critical temperature is exceeded where the apparatus is quiescent and not subject to vibration, but this is not a serious defect, in actual practice, as shipments are normally and inevitably subject to vibration, and a normally immobile sterilizing autoclave may easily be jarred sufficiently to restart the thermally controlled timing apparatus of the present invention.

It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory of the invention but are not re strictive thereof.

Referring now in detail to the present preferred and illustrative embodiment of the invention as shown in FIG- URES 1 to 4, there is shown a temperature controlled, totalizing timing apparatus which is adaptedto totalize and register the total of the periods of time during which the timer has been subjected to a temperature in excess of a given temperature. Thus, for a timer adjusted to a release temperature of about 120 C., no time will be registered or totalized so long as the timer does not exceed about 120 C., but it will register and totalize all of those periods during which the timer temperature exceeds about 120 0, thereby indicating, for example, whether or not the desired degree of sterilization has been positively achieved. Alternatively, any other release temperature may be chosen for the totalizing release of the timing apparatus.

'As embodied, the timing mechanism is'enclosed within a substantially moisture-proof and air-tight casing 10 which also serves to minimize external stoppage of the aosaass plates 16 and 18 with the other end of the spring fast to a winding shaft 22 which may be manually rotated by pinion 24 and gear 26, which gear is rotatable on a stud 28 projecting from plate 16. Gear 26 is provided with a sleeve 30 to which a winding and indicating knob 32 may be turned manually to wind the spring motor and also'se'rves to indicate the total of the periods during which the timing mechanism has run, by reference to the hour markings on the cover plate of the casing 10. Gear 34 is mounted on shaft 22 and is driven from spring 1 2 by means of the ratchet clutch 36 through friction clutch 3-8, Gear 34 drives the gear train 40, 42 and 44 to drive escapement wheel 46, which is controlled in its running by the escapement pallet lever 48, balance wheel 50, and

hair spring'52, the parts 40 to 59 being rotatably and pivotally mounted in bearings formed in the frame plates '18 and 20. These parts need not be described in more detail as they may be similar to those of conventional timers, and are so shown.

In accordance with the present invention means are provided which normally engage a portion of the gear train and prevent its running, but which are released to contained within a small depression formed in the plate surrounding the end of shaft 54, so that on melting, the mass 58 is held in place by cohesion and surface tension and when frozen binds the end of shaft 54' against movement, although it need not wet the shaft. Where the plate 29 is of brass, the meltable mass 53 may be of Woods' metal, which will wet the brass.

In use, the modification shown in FIGURE 5 serves the same purpose as the preferred form shown in FIGURES '1 to 4, and operates in the same mannen'except that the molten mass 58 .is held in place solely by its own cohesion and by the wetting of the surface of plate 20.

The temperature controlled timers of the present invention may be used in various manners, as within a package of surgical gauze or bandages which are subjected to sterilization, within a carton of packaged frozen food or whole blood, or in the interior of an autoclave, the selection of the meltable material being suitably chosen to correspond to the critical temperature of the material being sterilized or maintained frozen or refrigerated.

preferred embodiment, and as shown in FIGURES 3 and 4 the upper end of shaft 54 extends through plate 26) and is formed as a thin flat member 56 which is surrounded by a mass of meltable material, such as an alloy or a crystalline compound 58, which is retained adjacent the shaft end by means of a small metal cap 60, welded or soldered to the face of plate 20, as at 62.

Among the suitable materials are the lead-tin-bisruuth alloys, which can be adjusted for melting temperatures by suitably proportioning-the percentage composition of the alloy. One such suitable alloy is Woods metal. It is preferred to use, however, sharply melting substances, such as crystalline compounds, which may be selected to have the desired melting point, and stability. Thus for a temperature of 119 C., iodoform may be used. The following are typical of other compounds which may be used for other melting temperatures:

C., M.P. Succinic anhydride about 119.6 p-Xylene 13.2 l-phenyl-Z propanone l5 .4 l-methyl-imidazole 6.

When the melting temperature of the material constituting the. mass 5'8 is exceeded, the shaft 54 is free to rotate as in a conventional timer, until the temperature decreases and allows the mass 53 to congeal, at which time, rotation of the gear train and running of the timer is prevented. As the timer runs, pointer 32 moves counterclockwise across the-markings on the cover of case it to register the total time of running since the timer was last wound. Friction clutch 38 allows the knob to be moved in either direction, and movement in a clockwise direction causes spring 12; to be wound, at the same time that g the timer is, reset.

To-prevent leakage of the molten material in mass 53, shaft 54 may be mounted in a sleeve bearing 64 set in plate 20 and may also be provided with a sleeve 66 which forms a relatively close seal with the inner face of the sleeve bearing 64.

FIGURE 5 illustrates a simpler and modified form of the invention in which the meltable mass 58' is of a material which will wet the surface of the plate 2%! and is 1 mass of metal alloy having a sharp melting point en-.

V The invention in its broader aspects is not, limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims Without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

l. A temperature controlled timer for totalizing the time that the timer is subjected to a temperature exceeding a given temperature, comprising: a frame having at least two spaced apart, substantially parallel plates, a powered gear train rotatable in said frame, means driven by said powered gear train for registering the time of running of said gear train, escapement means mounted in said frame controlling the rate of running of the gears, a mass of metal alloy having a sharp melting point engaging one of said shafts in said gear train and engaging one of said plates and means for retaining said alloy adjacent the shaft it normally engages after the melting point of said metal alloy is exceeded.

2. A temperature controlled timer for totalizing the time that the timer is subjected to a temperature exceeding a given temperature, comprising: a frame having at least two spaced apart, substantially parallel plates, a powered gear train rotatable in said frame, means driven by said powered gear train for registering the time of running of said gear train, escapement means mounted in said frame controlling the rate of running of the gears, a mass of metal alloy having a sharp melting point engaging one of said shafts in said geartrain and engaging one of saidplates and a hollow cap fixedly attached to one of said plates for retaining said alloy adjacent the shaft it normally engages after the melting point of said metal alloy is exceeded.

3. A temperature controlled timer for totalizing the time that the timer is subjected to a temperature exceeding a given temperature, comprising: a frame having at least two spaced apart, substantially parallel plates, a powered gear train rotatable in said frame, means driven by said powered gear train for registering the time of running of said gear train, escapement means mounted in said frame controlling the rate of running of the gears, a

gaging one of said shafts in said gear train and engaging one of said plates and a recess formed in one of said plates for retaining said alloy adjacent the shaft it nor-- mally engages after the melting point of said metal alloy is exceeded.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Swanberg May 9, 1922 Tyler July 24, 1928 5 Denman Mar. 3, 1931 Mayers July 2, 19 35 Adolf Nov. 18, 1947 6 Zickrick Nov. 28, 1950 Brosseau Aug. 14, 1951 Ross June 10, 1952 Cafiier et al Dec. 23, 1952 Brubaker et a1. Jan. 13, 1953 Wiley Mar. 29, 1955 Modes et a1 June 17, 1958 *Bondurant July 1, 1958 

